Comparison of the in-soil hatching responses of Globodera rostochiensis and G. pallida in the presence and absence of the host potato crop cv. British Queen

Experiments were conducted in a field in Co. Cork, Ireland, to investigate the hatching behaviour of the two potato cyst nematode (PCN) species, Globodera rostochiensis and G. pallida, in soil in the presence and absence of a host potato crop cv. British Queen. In order to compare the hatching behaviour of the two PCN species in the field, standardised populations of each PCN species (produced under identical conditions for the two previous generations and extracted without desiccation) were inserted into the field in tissue-embedding cassettes by means of a novel 'harpoon' insertion tool. Inserting cassettes of both PCN species at different distances from host potato plants and destructively sampling the contents of the cassettes over the first 8 weeks after plant emergence revealed that there was no significant difference in the hatch of either PCN species around the host plant. Hatches in excess of 80% for both PCN species were recorded 8 weeks after plant emergence over a range of depths (10-40 cm) and distances (10-50 cm) around the host potato plants. Substantial hatches of G. rostochiensis (82%) and G. pallida (88%) were also recorded at a depth of 20 cm in the furrow at harvesting. Monitoring the rate of spontaneous hatching of G. rostochiensis and G. pallida in the absence of host potato plants over the spring and summer months (a 20-week period) revealed that there was a significant difference in the rate of spontaneous hatching between the two PCN species, with G. rostochiensis juveniles hatching in greater numbers over the first 14 weeks than G. pallida juveniles. However, by mid-August the mean spontaneous hatch for both PCN species within the top 30 cm of soil was found to be 37%.